This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Retinol and its metabolites participate in many physiological processes, such as growth, development, reproduction, cellular differentiation, and vision. Rats fed with retinol-free and all-trans-retinoic acid (atRA)-supplemented diet fail to reproduce. It has been shown that retinol is required no later then day 10 of gestation in order to prevent fetal resorption in the vitamin A deficient, atRA-supplemented (VAD-RAS) female rats. Metabolic studies on all trans retinol in day 10 conceptuses of vitamin A deficient, retinoic acid supplemented rats led to the isolation and identification of a novel metabolite, the isomers of 2-(hydroxymethyl)-3-methyl-5-(2'-oxopropyl)-2,5-dihydrothiophene. In continuation of our biological studies of this metabolite, we synthesised the cis and trans isomers of the metabolite. Configurations of these final isomers as well as their precursors are to be determined by 1H, 1H COSY 2D spectra and 1H NOE difference spectroscopy to compare the isomers with the naturally occurring ones.